Improve the ICE message for invalid nullary intrinsic calls by saethlin · Pull Request #148118 · rust-lang/rust

saethlin · 2025-10-25T22:06:01Z

In #148104, we found the panic message here rather confusing, and (if I'm reading the tea leaves right) that's because the intended audience for either side of the phrase is very different. I think this is more clear if/when this is encountered by users.

I expect this ICE to be hit in practice by people calling the size_of and align_of intrinsics, so it's now kind of helpful for those users too.

The original effort to stop backends from needing to support nullary intrinsics added a note to all these const-only intrinsics, but when #147793 ported two more the paragraph wasn't added. I've added it.

rustbot · 2025-10-25T22:06:04Z

Some changes occurred in compiler/rustc_codegen_ssa

cc @WaffleLapkin

rustbot · 2025-10-25T22:06:07Z

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folkertdev · 2025-10-25T22:12:23Z

I expect this ICE to be hit in practice by people calling the size_of and align_of intrinsics. Maybe we should also add specific guidance for those users?

In this particular case it would have been helpful to know that the problem is calling the intrinsic directly. I did not consider that that might be happening (and core::mem::size_of logically calls the intrinsic, so the error talking about intrinsics didn't surprise me).

So yeah some note about how directly calling these intrinsics is discouraged (or some stronger word: it just does not work) would have helped.

Noratrieb

r=me after reflowing, this sounds good

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saethlin · 2025-10-25T23:56:50Z

@bors r=Noratrieb rollup

bors · 2025-10-25T23:56:52Z

📌 Commit 07f144e has been approved by Noratrieb

It is now in the queue for this repository.

dianqk

Should we leave a comment stating that this can only be called at compile time? I can see this comment in some intrinsics (like needs_drop), but not in align_of. When I see Nullary intrinsic align_of must be called in a const block, I don't understand why this must be called in a const block.

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saethlin · 2025-10-26T00:08:36Z

I'll come back to that.
@bors r-

rustbot · 2025-10-26T01:32:41Z

Some changes occurred to the intrinsics. Make sure the CTFE / Miri interpreter
gets adapted for the changes, if necessary.

cc @rust-lang/miri, @RalfJung, @oli-obk, @lcnr

saethlin · 2025-10-26T01:33:44Z

I see what you meant. #142839 added a paragraph to the docs for all affected intrinsics then #147793 added size_of and align_of to this list of const-only intrinsics, but didn't add the paragraph for them.

dianqk

LGTM. Thanks!

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dianqk · 2025-10-26T01:37:29Z

@bors r=Noratrieb,dianqk

bors · 2025-10-26T01:37:31Z

📌 Commit 7a0d9c8 has been approved by Noratrieb,dianqk

It is now in the queue for this repository.

…ug-msg, r=Noratrieb,dianqk Improve the ICE message for invalid nullary intrinsic calls In rust-lang#148104, we found the panic message here rather confusing, and (if I'm reading the tea leaves right) that's because the intended audience for either side of the phrase is very different. I think this is more clear if/when this is encountered by users. I expect this ICE to be hit in practice by people calling the `size_of` and `align_of` intrinsics, so it's now _kind of_ helpful for those users too. The original effort to stop backends from needing to support nullary intrinsics added a note to all these const-only intrinsics, but when rust-lang#147793 ported two more the paragraph wasn't added. I've added it.

Rollup of 4 pull requests Successful merges: - #145665 (Don't require `T: RefUnwindSafe` for `vec::IntoIter<T>: UnwindSafe`) - #147728 (tests: activate misspelled `gdb-check` in `function-arg-initialization.rs`) - #148097 (tests/debuginfo/closures.rs: Activate misspelled `cdb-check`) - #148118 (Improve the ICE message for invalid nullary intrinsic calls) r? `@ghost` `@rustbot` modify labels: rollup

…ug-msg, r=Noratrieb,dianqk Improve the ICE message for invalid nullary intrinsic calls In rust-lang#148104, we found the panic message here rather confusing, and (if I'm reading the tea leaves right) that's because the intended audience for either side of the phrase is very different. I think this is more clear if/when this is encountered by users. I expect this ICE to be hit in practice by people calling the `size_of` and `align_of` intrinsics, so it's now _kind of_ helpful for those users too. The original effort to stop backends from needing to support nullary intrinsics added a note to all these const-only intrinsics, but when rust-lang#147793 ported two more the paragraph wasn't added. I've added it.

Rollup of 2 pull requests Successful merges: - #148097 (tests/debuginfo/closures.rs: Activate misspelled `cdb-check`) - #148118 (Improve the ICE message for invalid nullary intrinsic calls) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 2 pull requests Successful merges: - #148118 (Improve the ICE message for invalid nullary intrinsic calls) - #148134 (Add myself as a windows-msvc maintainer) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #148118 - saethlin:nullary-intrinsic-check-bug-msg, r=Noratrieb,dianqk Improve the ICE message for invalid nullary intrinsic calls In #148104, we found the panic message here rather confusing, and (if I'm reading the tea leaves right) that's because the intended audience for either side of the phrase is very different. I think this is more clear if/when this is encountered by users. I expect this ICE to be hit in practice by people calling the `size_of` and `align_of` intrinsics, so it's now _kind of_ helpful for those users too. The original effort to stop backends from needing to support nullary intrinsics added a note to all these const-only intrinsics, but when #147793 ported two more the paragraph wasn't added. I've added it.

…ug-msg, r=Noratrieb,dianqk Improve the ICE message for invalid nullary intrinsic calls In rust-lang#148104, we found the panic message here rather confusing, and (if I'm reading the tea leaves right) that's because the intended audience for either side of the phrase is very different. I think this is more clear if/when this is encountered by users. I expect this ICE to be hit in practice by people calling the `size_of` and `align_of` intrinsics, so it's now _kind of_ helpful for those users too. The original effort to stop backends from needing to support nullary intrinsics added a note to all these const-only intrinsics, but when rust-lang#147793 ported two more the paragraph wasn't added. I've added it.

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Oct 25, 2025

rustbot assigned dianqk Oct 25, 2025

saethlin mentioned this pull request Oct 25, 2025
ICE when using size_of in rust-lang/stdarch tests on i686-pc-windows-msvc#148104
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Noratrieb approved these changes Oct 25, 2025
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saethlin force-pushed the nullary-intrinsic-check-bug-msg branch from d890b26 to 07f144eCompare October 25, 2025 22:41

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Oct 25, 2025

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bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Oct 26, 2025

Improve the ICE message for invalid nullary intrinsic calls
7a0d9c8

saethlin force-pushed the nullary-intrinsic-check-bug-msg branch from 07f144e to 7a0d9c8Compare October 26, 2025 01:32

dianqk approved these changes Oct 26, 2025
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bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Oct 26, 2025

Zalathar mentioned this pull request Oct 26, 2025
Rollup of 4 pull requests #148123
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Zalathar mentioned this pull request Oct 26, 2025
Rollup of 2 pull requests #148127
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Zalathar mentioned this pull request Oct 26, 2025
Rollup of 2 pull requests #148136
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bors merged commit 3bf838d into rust-lang:masterOct 26, 2025
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rustbot added this to the 1.93.0 milestone Oct 26, 2025

saethlin deleted the nullary-intrinsic-check-bug-msg branch November 26, 2025 00:21

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